<!DOCTYPE html>
<html lang="en">

<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
  <script src="../js/jquery-1.10.1.min.js"></script>
  <style>
    html {
      height: 10000px;
    }

    .group {
      position: fixed;
      right: 20px;
      bottom: 20px;
    }
  </style>
</head>

<body>
  <div class="group">
    <button>设置</button>
  </div>
</body>
<script>
  // scrollTop()  获取和设置 滚动条距离文档左边的位置

  window.onscroll = function () {
    var scrollTop = document.documentElement.scrollTop || document.body.scrollTop;

    $(document).scrollTop();

    console.log($(document).scrollTop(), scrollTop);
  }

  $("button").eq(0).click(function () {
    // 设置
    // document.documentElement.scrollTop = 0;

    // window.scrollTo(0,0)
    // window.scrollTo({
    //     top:0,
    //     behavior:"smooth",
    // })

    $(document).scrollTop(0)
  })


</script>

</html>